package cn.hls.web.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 
 * 验证码
 * @author deqing.chedq
 *
 */
public class RandomCodeServlet extends HttpServlet{

	/**
	 * 
	 */
	private static final long serialVersionUID = -3686788052168905613L;
	//private static Log logger = LogFactory.getLog(RandomCodeServlet.class);
	
	// 验证码图片的宽度
	private int width = 60;
	// 验证码图片的高度
	private int height = 20;

	@Override
	public void init() throws ServletException {
		// TODO Auto-generated method stub
		super.init();
		//logger.debug("四位数字验证码初始化");
	}

	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		BufferedImage buffImg = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics2D g = buffImg.createGraphics();

		// 创建一个随机数生成器类
		Random random = new Random();
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, width, height);

		// 创建字体,字体的大小应该根据图片的高度来定
		Font font = new Font("Times New Roman", Font.PLAIN, 18);
		// 设置字体.
		g.setFont(font);

		// 画边框.
		g.setColor(Color.BLACK);
		g.drawRect(0, 0, width - 1, height - 1);

		// 随机产生160条干扰线,使图象中的认证码不易被其它程序探测到
		g.setColor(Color.GRAY);
		for (int i = 0; i < 10; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x, y, x + xl, y + yl);
		}

		// randomCode用于保存随机产生的验证码,以便用户登录后进行验证
		StringBuffer randomCode = new StringBuffer();
		int red = 0, green = 0, blue = 0;

		// 随机产生4位数字的验证码
		for (int i = 0; i < 4; i++) {
			// 得到随机产生的验证码数字
			String strRand = String.valueOf(random.nextInt(10));

			// 产生随机的颜色分量来构造颜色值,这样输出的每位数字的颜色值都将不同
			red = random.nextInt(200);
			green = random.nextInt(200);
			blue = random.nextInt(200);

			// 产生随机高度 13至height之间
			float imght = 0;
			while (imght <= 12) {
				imght = Float
						.parseFloat(String.valueOf(random.nextInt(height)));
			}
			// 用随机产生的颜色将验证码绘制到图像中
			g.setColor(new Color(red, green, blue));
			g.drawString(strRand, 13 * i + 6, imght);

			// 将产生的四个随机数组合在一起
			randomCode.append(strRand);
		}
		// 将六位数字的验证码保存到Session中
		HttpSession session = req.getSession();
		session.setAttribute("randomCode", randomCode.toString());

		// 禁止图像缓存
		resp.setHeader("Pragma", "no-cache");
		resp.setHeader("Cache-Control", "no-cache");
		resp.setDateHeader("Expires", 0);
		resp.setContentType("image/jpeg");
		
		// 将图像输出到Servlet输出流中
		ServletOutputStream sos = resp.getOutputStream();
		ImageIO.write(buffImg, "jpeg", sos);
		sos.close();
	}
}
